My Class

1

IE 552 Mechanics of Musculoskeletal System Dr.
Andris Freivalds Class 28
2
Case-Control ? Odds Ratio

• OR prev odds exp
• prev odds unexp
• OR pa/(1- pa)
• pb/(1- pb)
• (a/c)/(b/d)

3
Cohort Study ? Risk Ratio

• Rexp exp inj
• all exposed
• a/(ac)
• Runexp b/(bd)
• RR Rexp/Runexp
• a(bd)
• b(ac)

4
Multivariate Modeling -1

• y ß0 ß1x1 ß2x2 .. ßnxn e
• Logistic (logit) function y 1 e-(ß0
  ß1x1)-1

ln y/(1-y) ß0 ß1x1
5
Multivariate Modeling - 2

• ln y/(1-y) ß0 ß1x1

6
(No Transcript)
7
ROC Curve
8
Classification Performance
9
Quality of Epidemiological Studies

• Need to demonstrate exposure
• Need to diagnose problem
• Need to show causality
• Temporality
• Temporal contiguity
• Covariance of exposure and outcome
• Congruity of exposure and outcome
• Plausability

10
Details for Quality

• Clear definition of exposed/non-exposed
• Participation rates gt 70
• Physical examination for cases/non-cases
• Blinded study
• Exposure measures well defined

11
Evidence for WRMSD Risk Factors
12
(No Transcript)
13
(No Transcript)
14
Comments on Epidemiological Studies
15
Iatrogenesis (Contrarian View)

• Disease state from autosuggestion
• Rapid ? WRMSDs in Australia, 1970s
• Hadler in U.S
• Reasoning for iatrogenesis
• Non-healthy state needs diagnosis
• Workers Comp requires fit
• Adversarial system
• Media sensationalism
• Strong union support